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Well I got my forks back together, I never found a good diagram of the midvalve, so I was extra careful taking my other one apart and laid it out in order. I took pictures and will post when I feel like it.

The thing that made this difficult is that I couldn't get the rod that the midvalve mounts to out of the the cartridge. There is a ring about 1/3 of the way down the rod that appears to be swaged on, and prevents the rod from coming out far enough to easily work on the midvalve stacks. Surely the pro's don't put up with having to poke each shim in there and try to get it to slide down the rod with very little clearance.

How do you get that rod out of the cartridge so you can work on the midvalve?

Well my 2001's had a two piece nut thing (shown in the KYB fork service reference) that came off and allowed the rod to slide out the bottom. My 1997's had to have the "stakes" drilled out of the top of the cartridge to take it apart. Not sure about your year.

Well...so...how'd it come out?

I mean...if you feel like answering and all.............

Well, If you mean "How do they work?" I dunno, haven't been able to ride cuz of all the snow we got, unless I go to an MX track, and I been too busy anyway with refurbing a bathroom, daughter's ice show, working, life in general.

If you mean how'd it go getting them back together, it was kind of a bitch. I had to get all the shims and other parts out and back on inside the narrow confines of the cartridge tube, because I couldnt figure out how to get the rod out of the tube. I ended up taking a couple hours trying to do what should be a 15 minute job. I had a real tough time getting this little metal sleeve to line up in the recess in the valve body, and then get a spring over it, and then slide it into the tube, over the rod without coming apart and misaligning.

Bottom line is it's back together and I think it's correct, but I didn't mess with changing anything other than putting new seals, wipers and bushings in. I really wanted to do that, but I'll just test it a bit before I do.



This is the top of the cartridge and that @$#%ing ring that prevents the rod from coming through.



This is the order of parts I went with. I had no idea the midvalve had all that on there. I took the first one apart thinking one of the O-rings in my rebuild kit went around the piston, and it all came apart. Very dumb. Then I had no clue what order the parts go back together in.



That's a closeup of the midvalve.

I'm not taking this crap apart again until I find out how the pro's work on them . Everything went pretty easy in the rest of the rebuild, and if I could have had access to the midvalve that would have been easy too. I did make a cartridge holding tool out of a piece of gas pipe that made it real easy to torque the base valve onto the cartridge tube. Very simple to make, you just cut the tip to allow the tabs on the top of the cartridge to slide in, then drill a hole through the other end slide a screwdriver through.

er.... I am going to send mine in then....

LOL

Rather than that, make someone tell us how it's supposed to be done. If you could slide the tube up the rod far enough to get at the parts it would be easy. I felt like I was repairing the Hubble telescope at teh end of a slinky.

I felt like I was repairing the Hubble telescope at teh end of a slinky.

And...normally you work on the Hubble without a slinky?


Re: 'Then I had no clue what order the parts go back together in.

The way they are laid out looks right. Wide to narrow until you get to a point where there is something real small right next to something wide again (crossover I think), then it's wide to narrow again.

The initial wides (of which you have WAY too many!!!) go against the piston ports.

What is the thickness of those shims?

I'm sure you know more than you profess to.......

Re: taking it apart.

I don't know.

What is the fashion by which the top of the cartridge is attached TO the tubular part of the cartridge? It's two different metals..it is joined somehow. Threaded? Pressed? Staked? Swaged?

ANY markings on that circumference will indicate something that needs to be milled out/off. If no such attachment pins exist, it would be heat and threads.

That ring on the rod...how is it 'attached'?

Isn't this fun!!??

Not having metric calipers, I didn't get into documenting the shim stack, I just checked that they were the same thickness and diameter between the "known good", and the randomized midvalve.

That cartridge top is attached by magic. It does not appear to be welded, I thought it looked to be screwed ( a lot like me). I put the + sign looking end in my vise and attempted to twist the tube off with a big screwdriver shaft through the hole at the end. I got the feeling dollar $igns were about to start flying out the window, so I stopped. Maybe there is some bodacious thread locker in there, but I didn't try heat.

The ring on the rod is swaged into the groove in said rod. Does not look to be a commonly removed part.

The power bill alone from my internet searches on the topic of proper disassembly of this cartridge would have gone a long way toward funding a professional rebuild (but my experience with paying others to do things for me placed me on this road in the first place).

oh, and the thickness of the shims was about .004" the width, I just don't remember.

The .004" part is what I was after... or .10mm. A good number of folks (bradf is one) prefer the .10mm shims..as opposed to the .006" (.15mm) my valves have in 'em.

Heat is required (so I've read a few times) for cartridge disassembly. Well..obviously in those cases that require heat.

Quite a bit of it, too (so I've read...blah, etc. and yada).

Re: 'I got the feeling dollar $igns were about to start flying out the window, so I stopped.'

Words of a wise man.

....Where's the quote from?

I vote for heat......at your own risk:) That is usually how I get myself in trouble, but at least it gets me past the task at hand and on to another problem.... A propane torch would probably soften the loctite nicely.

'High Heat' Loctite I recall is around 450º break......

Doesn't have to be red-hot!

All good thoughts. For now, the snow has receded , the riding areas are due to open tomorrow, I think I will ride and wait for the most hollowed and sanctimonious Bradf to chime in before I endeavor to screw with my forks again. Besides, awaiting in my stable is an '05 YZ125, replete with air-oil-seperate forks, 193 lb dry weight, more HP than my 220 could dream of... and due to my son's ever spiraling downward grades... in want of a rider. It's good to be King!

Just a follow up on this.. I PM'd bradf and he was nice enough to respond with his prodigious knowledge on the topic. He said the '03's are a little different in that the ring on the shaft doesn't come off, so you have to remove the cartridge top as CC suspected. Actually I had suspected that too but chickened out after feeling like I was gonna break it. bradf says to secure the cartridge holding tool in a vise and heat the cartridge to around 500° to break the loctite on it, then it should unscrew. He recommended blue loctite for reassembly.

CM - One possible consideration for your dilemna . . .

I ran into a similar problem in cartridge disassembly on the YZ forks I've got. I ended up contacting MX-Tech and subsequently sent them in to be rebuilt (actually, that's a lie - I took the nut off of the bottom end of one of the cartridges and had things come loose with no way to fix them - I HAD to do something).

They took both apart, rebuilt/replaced a few things, then reassembled and sent them back. I talked to Jeremy Wilkens himself and he said it can be very difficult to take the cartridges apart without some specific tools/clamping/whatever. Some seem to be able to do it from what I've read, I just started marring the outside of the cylinders and such and stopped short of damage (money out the window thing). Jeremy said NOW it would be much easier to disassemble the cartridges if I want to go foolin' with the shims. Haven't done so yet but will when I retrofit with some of them fancy gold valves.

So that's another possibility - send the cylinders out (save postage) and let the pros take 'em apart for the first time. Maybe get 'em cleaned up / rebuilt. Then modify to your liking

**** EDIT ****

By the way the cylinder tops on my '98 YZ125 forks look exactly like the tops of yours, for what it's worth . . .

Good thinking Jeb. on my cartridges there are holes drilled through the bottoms of the tubes, so you can get a thick screw driver through there to twist. I think I need to go a little heavier on the fork springs anyway, so when I do that I'm going to try to get them apart and make some changes to the midvalve stack like bradf did. I think what I'm shooting for is a bit closer to a GNCC type setup.